Plasticizers are materials added to resinous compositions to increase the deformability thereof; i.e., to make them "softer". Technically, plasticizers are diluents or solvents with low volatility, causing them to remain in the resinous composition during curing or other processing. Their presence in the composition reduces cohesive bonds among the resin molecules, allowing them to flow past each other, thereby lending a degree of deformability to the resinous composition on a macroscopic level.
EP 553651 discloses bissulfonamide plasticizers for use with thermoplastic adhesive materials. U.S. Pat. No. 5,264,474 discloses mixtures of monosulfonamides and mixtures of bissulfonamides suitable for use as plasticizers. U.S. Pat. No. 4,946,933 discloses toluenesulfonamide plasticizers used in conjunction with adhesives derived from polyoxyalkylene amines.
Typically, the adhesive compositions used in vacuum forming processes comprise a film-forming material impregnated with a plasticizer. Vacuum forming is a conventional process for adhering thermoplastic materials to contoured substrates, particularly in the automotive industry. For example, a thermoplastic material (e.g., polyvinyl chloride flexible sheeting) can be laminated onto automobile parts such as consoles, dash boards, door panels, and other interior surfaces using vacuum forming. The substrates can be any conventionally used material, such as acrylonitrile-butadiene-styrene terpolymer (ABS) or fiberboard. The process involves coating the substrate with an adhesive, heating the thermoplastic material past its softening point, draping the thermoplastic material over the substrate, and applying a vacuum through the substrate to pull the thermoplastic material onto the contours of the substrate.
Sulfonamide plasticizers that are N-substituted with lower alkyl groups tend to be volatile and may evaporate from the adhesive composition during the life of an automobile, only to recondense on adjacent substrates, particularly windshields or windows, causing fogging or an unacceptable oily residue.
It would be desirable to provide a composition suitable for use as a non-fogging plasticizer in a resinous composition such as a vacuum forming adhesive, that overcomes the drawbacks of the prior art.
SUMMARY OF THE INVENTION
In accordance with the present invention, a composition of matter is provided comprising a mixture of:
(i) at least one alkyl aromatic sulfonamide containing from 12 to 40 carbon atoms total and at least six carbon atoms in the alkyl group; and PA1 (ii) at least one polyether aromatic sulfonamide different from (i) and having the following structure: EQU Q--[(OCH(R)CH(R)).sub.y --NH--SO.sub.2 --A].sub.z. PA1 (i) at least one alkyl aromatic sulfonamide containing from 12 to 40 carbon atoms total and at least six carbon atoms in the alkyl group; and PA1 (ii) at least one polyether aromatic sulfonamide different from (i) and having the following structure: EQU Q--[(OCH(R)CH(R)).sub.y --NH--SO.sub.2 --].sub.3. PA1 a) a film-forming material; and PA1 b) a plasticizer for the film-forming material; the plasticizer comprising the alkyl aromatic sulfonamide of (i) or mixtures of sulfonamides (i) and (ii) as described above. Preferred compositions are adhesive compositions. Such a composition is non-fogging and is suitable for use in a vacuum forming adhesion process. The plasticizer preferably comprises a mixture of sulfonamides (i) and (ii).
Q is selected from the following structures: ##STR2##
A is an aromatic group containing from 6 to 39 carbon atoms; L is an alkyl group containing from 1 to 20 carbon atoms or EQU A--SO.sub.2 --NHCH(CH.sub.3)CH.sub.2 --;
R is independently hydrogen or linear or branched alkyl groups having from 1 to 4 carbon atoms; x ranges from 0 to 40; y ranges from 2 to 40; z ranges from 1 to 3; and a ranges from 0 to 40. Also provided is a resinous composition comprising a film-forming material and a plasticizer, wherein the plasticizer comprises (i) or the mixture of (i) and (ii) above.
Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as modified in all instances by the term "about". Note further that the numerical ranges of values for subscripts in chemical structures are intended to encompass average values.